zonal vs progressive flow

Here's a question for our resident weather experts: what is the difference between "zonal flow" and "progressive flow"?<br><br>I see these terms used in the NOAA forecast discussions. The two different patterns of weather flow across our area must have significant implications for the current and future weather, but I haven't been able to figure out what these implications are.

Charles, I will draw from my Whatcom Comm. College Meteorology class of 1996. A progressive pattern is an active, busy jet stream with amplification (troughs and ridges). A zonal pattern is an active, busy jet stream with less amplification.....So, with winter weather, a zonal flow is preferred. (for us skiers) I remember living in the Sierras in 1997-98 and the Cascades in 1998-99, both years in which an almost constant zonal flow (especially Feb.) led to great, heavy snowfalls. I can still remember sitting in a diner on the west shore of Lake Tahoe, watching the weather channel, and seeing storms shaped like commas lined up from here to Japan ready to deliver huge amounts of snow!!.....On the other hand, a progressive pattern could include the dreaded Pin****le Ex***ss, due to the sometimes wildly fluxuating jet stream....

I'm not a meteorologist, but here is my take:<br><br>The two directions of flow are zonal, which is west-east and progressive, and meridinal, or S&gt;N or N&gt;S flow, which is created by high amplification of ridges and troughs. Meridinal flow tends to be stagnant or only very slowly progressive from west to east. <br><br>So, progressive means weather systems and ridges and troughs move relatively rapidly from west to east. Terms like stationary describe high amplitude patterns. <br>

Yes, so zonal and progressive are related. But, the zonal progressive pattern does not fluxuate as much as a non-zonal progressive pattern. The zonal storms are directed, more or less, between lattitude lines, be it to the sierras or the cascades, or the coast mtns. These storms are tightly wound, comma shaped storms when viewed on sattelite. (Not long sweeping fronts, sometimes led by warm streams of moisture/air from the south, sometimes creating precip. from so. cal. to bc.) The zonal flow storms tend to come "stacked up" off the coast, not letting high pressure build behind a front.....How does that sound?  

Direct from the NWS. <br>Progressive Flow or Progressive Pattern: An upper level flow pattern in which storm systems move along at a fairly regular pace.<br>Zonal Flow: Upper level flow that is essentially west to east and is usually quite fast. Can have many short wave troughs within it. <br>These are definitions provided to navigate the website discussions, yet are fairly generic.

Toby:<br><br>

Yes, so zonal and progressive are related. But, the zonal progressive pattern does not fluxuate as much as a non-zonal progressive pattern. The zonal storms are directed, more or less, between lattitude lines, be it to the sierras or the cascades, or the coast mtns.

<br><br>I certainly wouldn't argue with that. In concert with less fluctuation in pressure or amplitude comes the corollary that the systems which move more rapidly (are more progressive) and accordingly; freezing levels, which are related to upper atmospheric pressure, vary less from system to system and within systems.<br><br>The most stagnant systems are those that are oriented N&gt;S (or S&gt;N). For example, a negatively tilted front is one that is oriented NW&gt;SE, as opposed to the more normal, NE&gt;SW. These systems usually weaken as they slowly approach.<br><br>An Omega block is a dumbell shaped region of high pressure situated in the gulf of Alaska and usually extending along the entire west coast. This is probably the least progressive (most stable) pattern.<br><br>